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1. Field of the Invention
The present invention is in the field of mechanical actuators, particularly tension or traction device actuators, especially as used in automotive or furniture ergonomic mechanisms such as lumbar supports.
2. Prior Art
Ergonomic mechanisms such as lumbar supports are typically adjustable by mechanical means which may be activated and controlled at certain expense by motors, and at a lesser expense by levers, handwheels and the like. There is a continuing need for simplicity, durability and cost control in this area.
Ergonomic mechanisms are commonly designed to retain particular settings chosen by a repeat user for his or her individual comfort. Retaining an adjustment is often achieved by keeping a device like a lumbar support under pressure or tension, as by a traction cable. Settings need to be maintained through loading and unloading cycles, requiring brakes or locks for holding the settings. Serial adjustment must remain possible, requiring releases, overrides or clutches. In high volume markets such as automobiles or furniture, reducing costs and simplifying assembly of these multiple components are constant needs.
Simple levers are desirable adjustment devices, especially for automobiles. However, once a user selects a position for a device such as a lumbar support, the corresponding lever position frequently protrudes at an inconvenient angle. In automobiles, this can be particularly problematic in that clothing, seat belts and the like are easily caught on a lever that protrudes from the seat back where such levers are usually mounted. There is a need for a lever that can actuate an ergonomic mechanism like a lumbar support, maintain the selected position of it, and keep the lever in a home position where it is minimally intrusive.
The present invention is a ratcheting, locking clutch actuator, particularly for selectively positionable ergonomic devices like lumbar supports. The present invention uses a novel hanging scissors ratchet and lever to drive a geared shaft through a pre-selected number of degrees and thereafter return the lever to a home position.
Drive direction is selectable by a pair of facing ratchet pawls. Lever homing is by a biasing spring. The present invention combines the scissors ratchet and homing lever with a releasable, overrunning clutch and lock assembly.
A housing assembly offsets the scissors ratchet from a drive shaft. The lever shaft is preferably co-axial with a drive gear, and also with a retaining ring and eccentric hub which comprise a clutch. The clutch hub is engaged with a pulley in a pulley housing, again in a preferably co-axial configuration. The pulley is tractively engaged with one end of a tensioning cable. The other end of the cable is operatively engaged with a ergonomic device, such as a lumbar support.
Turning the lever one or more times through a pre-configured arc advances the pulley one direction to draw the cable into a selected position. The locking hub retains the pulley cable at the selected position while the ratchet/spring assembly homes the lever. Turning the lever the opposite direction reverses the drive gear and shaft, releasing the locking clutch hub and paying out the cable via the counter rotating pulley until a second selected position is reached, whereupon the second position is again locked by the clutch hub and the lever again homed by the biasing spring.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.